LOWER CRETACEOUS DEPOSITS CALIFORNIA AND OREGON

CRETACEOUS SEDIMENTARY DIVISIONS 67
As far as call be determined the so-called "Knoxville" are, in most instances
at least, no other than equivalents of tbe Paakenta group. In
the account given by Stanton (1S95, p. 22, 23) he states tbat
"The Crctaceoua rocks here, covering aa area about 5 miles long and 3 mile a
wide, arc in contact with raetaraorpiiic recke on the esai and with aarpentine and
peridotitfle on the west. Tbe striata, at moat exposures have a ateep dip and seem
to form a eyncline, complicated perhaps by fault* or minor folds."
The same view is expressed by Diller and Kay (1924) and has been confirmed
by tbe writer's personal inspection during a more recent visit.
Following this visit, E. L. Packard of the Oregon State College sent to the
California Academy of Sciences a considerable eollection of well-preserved
and diagnostic fossil Mollusca from beds exposed near Riddle, which throw
much light upon the age of the sequence occurring here. Many of the
species found here are described in this memoir for the first time. The
following list includes the mere important of these fossils:
PhyUoeeraJ IrinHente nov. Diekotomites ej-eflenenm nov.
P. occidcntale nov.
P. umpquaniuTTt nov,
P. ofemwwrwe nov.
Aucella crcuta Pavlow
A. crtttsicoilis Keyaerling
A. ISAUMIU Pavlow
A. injlnta. Toula
Venus callinae aav.
PlzuTomya laevigata
Pcriploma cf. reddigensit nov.
Pec ten (SyncycUmema) ap,
To this list may be added BcrriaseUa hyaiti (Stanton) and Acroteulhis
impressa (Gabb), as reported by Stanton (1895, p. 22, 23). The Lower
CretaeeouB (Paskenta) age of the strata from which these fossils were
taken can hardly be doubted. Many of the forms named in this list are
common in the Paakenta group in California, and near analogues of others
are found in it. Some of them have also been found in the Horsetown
group.
In 1913 Bruce G. Martin obtained a small collection of fossils from a
point 2 miles north of the mouth of Myrtle Creek, including Aucella
crassa Pavlow, A. lakuseni Pavlow, and A, terebratuloides Lahnsen, All
these species pertain to the Paskenta group of the Shasta series in California.
In tbe beds occupying the syncline at Riddle, no strata older than the
Paskenta group have been shown to exist, although older beds have been
reported. From near Nichols station, some miles southwest of Riddle,
Diller (1908, p, 375) has reported beds containing "typical specimens of
Aucella piochi Gabb' 1 and Mesozoic plants. The resemblance of the young
stages of other forms of Aucella to A, piochi Gabb necessitates a degree
of caution in their determination, and therefore of reserve in the acceptance
of hasty identification.
In the Dillard area north of Myrtle Creek (town), the "Myrtle formation"
extends over most of the area covered by the Roaeburg quadrangle,